DK141606B - Process for reforming a hydrocarbon and composite catalyst intended to carry out the process. - Google Patents

Description

(11) PRESENTATION 1U1606 MÉ2

1 ohI

\ RB

DENMARK lnt c '3 c 10 8 35/09 § (21) Application No. 2237 / (¾ (22) Filed dan 23 · 3PF · 1 S & 9 (23) Running days Apr 23, 19 ^ 9

(44) The application presented increase Q

promulgation issued on May 5, 19 ^ 0 THE DIRECTORATE OF THE PATENT AND TRADEMARKET (30> Precision gassed from the

Apr 24 1968 * 7? 3886, US

<71> UNIVERSAL OIL PRODUCTS COMPANY, 30 Algonquin Road, Des Plaines, 1111 = nois, US.

(73) Inventor: Ernest Leo Pollitzer, 9655 Fiarlov Avenue, Skokie, 1111 = nois, US.

(74) Plenipotentiary in the proceedings:

The engineering company Budde, Schou & Co.

(54) Process for reforming a hydrocarbon and composite catalyst for carrying out the process.

The present invention relates to a novel process for reforming a hydrocarbon as well as to a novel composite catalyst comprising alumina and intended for carrying out the process. This composite catalyst has been found to have exceptional activity and resistance to deactivation when used in a hydrocarbon reforming process which requires a catalyst having a hydrogenation dehydrogenation function coupled with a cracking function.

2 161606

Composite materials having a hydrogenation dehydrogenation function and a cracking function are widely used today as catalysts in many industries, such as the petroleum and petrochemical industries, to accelerate a variety of hydrocarbon conversion reactions. Generally, the cracking function is believed to be associated with an acidic material of the porous, adsorbent, heavy-meltable oxide type typically used as a carrier or carrier for a heavy metal component, such as metals or compounds of the metals of Group V through Group VIII of the Periodic Table. system. The hydrogenation dehydrogenation function is usually attributed to this metal component.

These composite catalysts are used to accelerate a variety of hydrocarbon conversion reactions, e.g. hydrocracking, isomerization, dehydrogenation, hydrogenation, desulfurization, cyclization, alkylation, polymerization, cracking and hydroisomerization.

In many cases, the commercial uses of these catalysts are in processes where more than one of these reactions takes place simultaneously.

An example of this type of process is reform in which a hydrocarbon feed stream containing paraffins and naphthenes is subjected to conditions which accelerate dehydrogenation of naphthenes to aromatics, dehydration of paraffins to aromatic compounds, isomerization of paraffins and naphthenes, hydrocracking of naphthenes and paraffins and similar reactions, to produce a product - high octane stream or rich in aromatic compounds. Another example is a hydrocracking process in which catalysts of this type are utilized to effect selective hydrogenation and cracking of high molecular weight unsaturated materials, selective hydrocracking of high molecular weight materials and other similar reactions to produce a generally lower boiling, more valuable product stream. A further example is an isomerization process in which e.g. a hydrocarbon fraction relatively rich in unbranched paraffin components is contacted with a dual-function catalyst to produce a product stream rich in isoparaffin compounds.

Regardless of the reaction involved or the particular process involved, it is essential that the dual-function catalyst not only exhibits its ability to perform its predetermined functions initially, but also has the ability to perform them satisfactorily for long-term period of time. The analytical units used in the art to measure how well a particular catalyst performs its intended functions in a particular hydrocarbon reaction are activity, selectivity and stability. As far as the discussion herein is concerned, these terms are defined as follows: (l) "activity" is a measure of the catalyst's ability to convert hydrocarbon reactants into products at a given severity level, where "severity level" means the conditions used, i.e. the temperature, pressure, contact time and presence of diluents such as Hg} (2) "selectivity" refers to the weight percent of the reactants which are converted to the desired product and / or products} and (3) "stability" refers to that rate. by which activity and selectivity change} it is obvious that less velocity means a more stable catalyst. In a reforming process, activity refers e.g. usually to the conversion that takes place for a given batch material at a given level of severity, and is typically measured by the octane number of the C + + product stream} selectivity refers to the C + - yield obtained at that particular level of severity. Stability is sometimes set equal to the rate at which the activity changes over time and to selectivity over time. Generally, however, a continuous reforming process is controlled to produce a C + + product with a constant octane number, the level of rigidity being continuously adjusted to achieve this result. Furthermore, the severity level of this process is usually varied by setting the conversion temperature in the reaction zone, so that the rate at which the activity changes is actually reflected at the rate at which the conversion temperature changes. As a result, changes to this last parameter are often taken as an expression of activity stability.

As is known to those skilled in the art, the main cause of observed deactivation, or instability, of these dual-function catalysts when used in a hydrocarbon conversion reaction is associated with the fact that coke is formed on the surface of the catalyst during the course of the reaction. More specifically, the conditions used in these hydrocarbon conversion reactions typically result in the formation of heavy, black, solid or semi-solid, high molecular weight carbonaceous material which covers the surface of the catalyst and reduces its activity by shielding its active centers from the reactants. In other words, the performance of this dual function catalyst is sensitive to the presence of carbonaceous deposits on the catalyst surface. Accordingly, the main problem encountered by researchers in this field is the development of more active and selective composite catalysts, such as 4 141606 are not as sensitive to the presence of these carbonaceous materials and / or have the ability to suppress the rate of formation of these carbonaceous materials on the catalyst. Expressed by performance parameters, the problem is to develop a dual-function catalyst that has superior activity, selectivity and stability. In particular, for a reforming process, the problem is typically referred to as displacement and stabilization of the yield-octane number relationship for the C, - + - product, with the yield expressing the selectivity and the octane number being proportional to the activity.

A dual-function composite catalyst has now been developed which possesses enhanced activity, selectivity and stability when used in such hydrocarbon conversion processes as e.g. isomerization, hydroisomerization dehydrogenation, hydrogenation, alkylation, dealkylation, ring closure, dehydration closure cracking, hydro cracking and reforming. In particular, it has been determined that a synergistic combination of a platinum group metallic component and a rhenium component by composition with a halogen-containing alumina support significantly improves the performance of hydrocarbon conversion processes that normally use dual-function catalysts. In addition, in the case of a reforming process, this novel catalyst by coupling with a substantially anhydrous reforming environment also allows the stability of the process to be even more markedly improved.

Accordingly, the present invention provides a composite catalyst comprising alumina and intended for practicing the process of reforming a hydrocarbon which is characterized in that the alumina is combined with a metallic component of the plate group, a halogen component and a rhenium component. said components being present in amounts which, in the composite catalyst, on an elemental basis, provide from ca.

0.1 to approx. 1.5% by weight of halogen, from approx. 0.05 to approx. 1.0% by weight plate group metal and from approx. 0.05 to approx. 1.0% by weight of rhenium.

It is preferred according to the invention that the composite catalyst has been reduced under virtually anhydrous conditions prior to its use in the reforming of hydrocarbons.

5 141606

It is further preferred according to the invention that the pre-reduced composite catalyst also contains a sulfur component in an amount of from 0.05 to approx. 0.5% by weight of the composite material.

The present process for reforming a hydrocarbon is in accordance with the above, in the manner in which the hydrocarbon is brought into contact with a composite catalyst at elevated temperature and pressure in the presence of hydrogen, and is characterized in that: For example, a catalyst comprising alumina, a metallic component of the plate group, a halogen component and a rhenium component is used, said components being present in amounts which, in the composite catalyst, on an elemental basis, provide from ca. 0.1 to approx. 1.5% by weight of halogen, from approx. 0.05 to approx. 1.0% by weight plate group metal and from approx. 0.05 to approx. 1.0% by weight of rhenium.

Conveniently, when the process of the present invention is used to reform a gasoline fraction, the gasoline fractions are contacted with the catalyst of the present invention under reforming conditions comprising a substantially anhydrous environment and in the presence of hydrogen, thereby forming a high number of reforms.

Other embodiments of the present invention relate to preferred catalytic components and the concentration of components of the catalyst, operating conditions for use in the hydrocarbon reforming processes, and other details as will be apparent from the following detailed description.

As stated above, the catalyst of the invention comprises alumina to which a platinum group component, a rhenium component and a halogen component are joined. Considering first the alumina used in the present invention, it is preferred that the alumina material is a porous adsorbent carrier having a surface area of from ca. 25 to approx. 500 m / g or more. Suitable alumina materials are the crystalline alumina known as gamma, eta and theta alumina, with gamma alumina providing the best results. In addition, the alumina carrier may contain minor amounts of other known, highly fusible, inorganic oxides, e.g. silica, zirconia and magnesium oxide. However, the preferred carrier is practically pure gamma alumina.

In fact, a particularly preferred carrier has an apparent bulk weight in the bulk of from 0.30 g / cirP to ca. 0.70 g / cit? and such surface area characteristics that the average pore diameter is from ca. 20 to about 300 Å, the pore volume is from approx. 0.10 to approx. 1.0 ml / g and the surface area is from approx. 100 to approx. 500 m / g.

The alumina support may be synthetically produced in any suitable manner or may be naturally occurring. Whatever type of alumina is used, it can be activated prior to use in one or more treatments, including e.g. drying, calcining and water vapor treatment, and it may be in a form known as activated alumina, activated alumina, porous alumina, alumina gel, etc. The alumina carrier may e.g. can be prepared by adding a suitable alkaline reagent such as ammonium hydroxide to an aluminum salt, for example, aluminum chloride and aluminum nitrate, in an amount which forms an aluminum hydroxide gel which, after drying and calcining, is converted to alumina. The aluminum oxide can be formed in any desired form, such as balls, pills, cakes, extrudates, powders or granules. For the purposes of the present invention, the sphere is a particularly preferred form of the aluminum oxide. Aluminum oxide beads can be prepared continuously by the known oil drop method which comprises forming an alumina hydrosol by any of the methods known in the art, and preferably by reacting metallic aluminum with hydrochloric acid, combining the hydrosol with a suitable gelling agent, and dripping. the resulting mixture to an oil bath maintained at elevated temperatures. The small droplets of the mixture remain in the oil bath until they solidify and form hydrogel balls. The spheres are then continuously removed from the oil bath and typically subjected to special aging treatments in oil and an ammonia solution to further improve their physical properties. The resultant, aged and gelatinous particles are washed and then dried at a relatively low temperature of from ca. 14 ° C to approx. 204 ° C and subjected to calcination at a temperature of from ca.

454 ° C to approx. 704 ° C for a period of approx. 1 to about 20 hours. This treatment causes the conversion of the alumina hydrogel to the corresponding crystalline gamma-alumina.

An essential component of the catalyst of the invention is a halogen component. Although the exact chemistry associated with the association of the halogen component with the alumina carrier is not fully known, it is customary in the art to refer to the halogen component as being associated with the alumina carrier or with the other components of the catalyst. This bonded halogen can be either fluorine, chlorine, iodine, bromine, or mixtures thereof. For the purposes of the present invention, these are fluorine and especially chlorine. The halogen may be added to the alumina support in any suitable manner, either during the preparation of the support or before or after the addition of the catalytically active metallic components. The halogen may e.g. as an aqueous solution of an acid, for example, hydrogen fluoride, hydrogen chloride or hydrogeribromide is added at any stage of preparation of the carrier, or to the calcined carrier. The halogen component, or a portion thereof, may be combined with the alumina during impregnation of the latter with the platinum group component, e.g. using a mixture of chloroplatinic acid and hydrogen chloride. In another situation, the alumina hydrosol typically used to form the alumina component may contain halogen and thus supply at least a portion of the halogen component to the finished composition, in any case the halogen will be composed with the alumina carrier in such a manner. that results in a finished composite material containing from approx. 0.1 # to approx. And preferably from about 1.5 #. 0.4 to approx. 0.9% by weight halogen, calculated on an elemental basis.

As noted above, the catalyst of the invention also contains a metallic component of the plate group. Although the present invention is specifically directed to a composite catalyst containing platinum (and to a method of using it), it is to be understood as comprising other platinum group metals, e.g. palladium, rhodium and ruthenium. The metallic component of the platinum group, such as platinum, may be present within the finished composite catalyst as a compound, e.g. an oxide, sulfide or halide, or in the free state. Generally, the amount of the metallic component 8 141606 from the plate group present in the final catalyst is small compared to the amounts of the other components associated therewith. In fact, the metallic component of the plate group is usually from about 0.05 to ca. 1.0 wt- $ of the finished composite catalyst, calculated on an elemental basis. Excellent results are obtained when the catalyst contains from ca. 0.5 to approx. 0.9 weight percent of the plate group metal.

The plate group metal can be incorporated into the composite catalyst in any suitable manner, such as by co-precipitation or co-gelatinization with the alumina support. ion exchange with the alumina carrier and / or alumina hydrogel, or by impregnating the alumina carrier and / or alumina hydrogel at any stage of its preparation and either after or before calcining the alumina hydrogel. The preferred process for preparing the catalyst involves the use of a water-soluble compound of the plate group metal for impregnating the alumina support. For example, platinum can be added to the carrier by mixing the latter with an aqueous solution of ehloroplatinic acid. Other water-soluble platinum compounds can be used as impregnation solutions, including, for example, ammonium chloroplatinate, platinum chloride and dinitrodiamino-platinum. Use of a platinum-chloro compound, such as chloroplatinic acid, is preferred as it facilitates the incorporation of both the platinum component and at least a minor amount of the halogen component in a single step. Hydrogen chloride is also usually added to the impregnation solution to further facilitate the incorporation of the halogen component. In addition, it is generally preferred to impregnate the carrier after it has been calcined to minimize the risk of washing away the valuable platinum metal compounds. However, in some cases, it may be advantageous to impregnate the carrier when in a gelatinized state. Following the impregnation, the resulting impregnated support is dried and subjected to a high temperature calcination or oxidation treatment identical to that described above for the description of the alumina carrier preparation.

Another essential component of the catalyst of the invention is the rhenium component. This component may be present as a free metal, as a chemical compound such as the oxide, sulfide or halide, or in a physical or chemical association with the alumina carrier and / or the other components of the catalyst. Generally, the rhenium component is used in an amount which results in a final catalyst containing from 0.05 to approx. 1.0 weight-rhenium, calculated as a free metal. The rhenium component can be incorporated into the composite catalyst in any suitable manner and at any stage in the preparation of the catalyst.

As a general rule, it is advisable to introduce the rhenium at a later stage of manufacture so that the precious metal will not be lost due to subsequent machining involving washing and purification treatments. The method of incorporating the rhenium component may involve impregnating the alumina support either before, during or after the other components mentioned above are added. The impregnation solution may in some cases be an aqueous solution of a suitable rhenium salt such as ammonium perrhenate, sodium perrhenate, potassium perrhenate and similar salts. In addition, an aqueous solution of rhenium halides, such as the chloride, can be used if desired. However, the preferred impregnation solution is an aqueous solution of perrhenic acid. In general, the rhenium component can be impregnated either before, simultaneously with or after the metallic component of the plate group is added to the support. However, it has been found that the best results are achieved when the rhenium component is impregnated simultaneously with the platinum group component. Therefore, a preferred impregnation solution contains chloroplatinic acid, hydrogen chloride and perrhenic acid.

A particularly preferred composite catalyst is obtained when the weight ratio of rhenium component to platinum group component (calculated on an elemental basis) is between approx. 0.05: 1 and approx. 2.75: 1 · This is especially true when the total weight of the rhenium component plus the platinum group component of the composite catalyst is between approx.

0.2 and approx. 1.5 wt. #, Preferably between ca. 0.4 and approx. 1.0 weight- #, calculated on an elemental basis. Accordingly, examples of particularly preferred composite catalysts are those containing: 0.1 wt # Re + 0.65 wt # Pt, 0.2 wt # Re + 0.55 wt # Pt, 0.575 wt - # Re + 0.575 wt # Pt, 0.55 wt # Re + 0.20 wt # Pt, and 0.65 wt # Re + 0.10 wt # Pt.

Regardless of how the components of the catalyst are combined with the alumina support, the finished catalyst will generally be dried at a temperature of from 95 ° C to approx. 5 ° C for a period of from about 2 to 24 hours or more and finally calcined at a temperature of approx. 571 ° C to approx. 595 ° C for a period of approx. 0.5 to 10 hours, preferably from ca. 1 to approx. 5 hours.

10 U1606

It is preferred that the resulting calcined composite catalyst be subjected to a practically anhydrous reduction prior to its use in the conversion of hydrocarbons. This step is designed to ensure a uniform and finely dispersed dispersion of the metallic components throughout the alumina support. In this step, as the reducing agent, preferably pure and dry hydrogen (i.e. containing less than 5 ppm E 2 O by volume) is used. The reducing agent is contacted with the calcined catalyst at a temperature of, among other things. 427 ° C to approx. 649 ° 0 and for a period of approx. 0.5 to 10 hours or more and, in any case, for a period of time effective for practically complete reduction of both metallic components to their elemental state. This reduction treatment can be carried out in situ as part of the commissioning (i.e., in the reaction chamber where it is to be used) if measures are taken to pre-dry the plant to a practically anhydrous state and if practically anhydrous hydrogen is used.

Although not essential, the resulting reduced composite catalyst may in some cases advantageously be subjected to a precipitation which is intended for incorporation into the composite catalyst of from 0.05 to approx. 0.50% by weight of sulfur, calculated as elemental. This presulfidation treatment is preferably carried out in the presence of hydrogen and a suitable sulfur-containing compound, for example hydrogen sulfide, a low molecular weight mercaptan or an organic sulfide. This process comprises treating the reduced catalyst with a sulfiding gas, such as a mixture of hydrogen and hydrogen sulfide, containing approx. 10 moles of hydrogen per moles of hydrogen sulfide under conditions which effect the desired incorporation of sulfur and which generally comprise a temperature which varies from ca. 10 ° C up to approx. 595 ° C or higher.

According to the present invention, an hydrocarbon charge mixture and hydrogen are contacted with a catalyst of the type described above in a hydrocarbon conversion zone. This contact can be achieved by using the catalyst in a system of fixed mass, a system of moving mass, a system of fluidized mass or of operation of the batch type. However, given the danger of loss of the valuable catalyst due to wear and tear and well known operating advantages, it is preferred to use a fixed mass system. In this system, a hydrogen-rich gas and the charge mixture are preheated by any suitable heating means to the desired reaction temperature and then passed into a conversion zone containing a fixed mass of the above-described catalyst type. It will be appreciated that the conversion zone may comprise one or more separate reactors with suitable means therebetween, ensuring that the desired conversion temperature is maintained at the access to each reactor. The reactants can be contacted with the catalyst mass in either upward, downward or radial flow, the latter being preferred. In addition, the reactants may be in the liquid phase, a mixed liquid-vapor phase, or vapor phase when they come into contact with the catalyst, however the best results are obtained in the vapor phase.

When the catalyst of the invention is used in reforming, the reforming system will comprise a reforming zone containing a fixed mass of the above-described catalyst type.

This reforming zone may be one or more separate reactors with suitable heating means therebetween, in compensation for the endothermic nature of the reactions taking place in each catalyst mass. The hydrocarbon feed stream charged to the reforming system will include hydrocarbon fractions containing naphthenes and paraffins boiling in the gasoline range. The preferred charge mixtures are those consisting essentially of naphthenes and paraffins, although in some cases aromatic compounds and / or olefins may also be present. A preferred group of charge mixtures include straight run gasoline, naturally occurring gasoline, synthetic gasoline, etc. On the other hand, it is often advantageous to charge thermally or catalytically cracked gasoline or higher boiling fractions thereof, termed heavy naphtha. "straight run" and cracked gasoline can also be used advantageously. The gasoline charge mixture can be a full-boil gasoline having an initial boiling point of from about 10 ° C to about 66 ° C and a final boiling point of between about 163 ° C and about 219 ° C, or it may be a selected fraction thereof, which will generally be a high-boiling fraction, commonly referred to as a heavy naphtha, for example a naphtha boiling in the range of 0 ° to 204 ° C. In some cases, it is also advantageous to charge pure hydrocarbons or mixtures of hydrocarbons which have been extracted from hydrocarbons which are, for example, a straight-chain paraffin, which must be converted to aromatic compounds. It is preferred that these charge mixtures, if necessary, be treated by conventional pretreatment methods to remove virtually all sulfur-containing, nitrogen-containing and water-releasing impurities therefrom.

In other embodiments of hydrocarbon conversion, the charge mixture will be of the conventional type usually used for the particular kind of hydrocarbon conversion being carried out. Yed e.g. in an isomerization, the charge mixture may be a paraffinic mixture rich in normal paraffins of 4-8 carbon atoms, or an n-butane-rich mixture or an n-hexane-rich mixture, etc. eg. heavy Hstraight run gas oil or heavy cracked eyclus oil. In addition, alkyl aromatic compounds can be conveniently isomerized using the present catalyst. Similarly, pure, or practically pure, hydrocarbons can be converted into more valuable products using the present catalyst. by any of the hydrocarbon conversion processes promoted by a dual function catalyst.

If the process of the invention is used in a reforming, it is an essential feature that the composite catalyst is used in a practically anhydrous environment. It is important that the total volume of water entering the reform zone from any source is kept at a level not exceeding 50 parts per square meter. million (ppm) by weight expressed as the weight of equivalent water in the charge mixture. By the term "equivalent water" is meant water which is present as water, plus the water which can be formed from water precursors present in the charge mixture. This can usually be achieved by careful regulation of the water contained in the charge mixture and The charge mixture can be dried using any suitable drying means, such as a conventional solid adsorbent with high selectivity for water, for example crystalline sodium or calcium aluminum silicates, silica gel, activated alumina, molecular sieves, anhydrous calcium sulfate, high surface area sodium and the like. Similarly, the water content of the charge mixture can be adjusted by suitable stripping in, for example, a fractionation column, in some cases a combination of adsorbent drying and distillation drying can be used advantageously to accomplish almost complete removal of water from the charge mixture. The charge blend is preferably dried to a level eau equivalent to less than 20 ppm. equivalent water * Generally, it is preferable to dry the hydrogen stream entering the hydrogen conversion zone to a level of approx. 10 ppm..water by volume or less. This can conveniently be achieved by contacting the hydrogen stream with a suitable desiccant, e.g. those mentioned above.

During reforming, a discharge current is withdrawn from the reforming zone, which discharge current is passed through a capacitor to a separation zone which is typically maintained at approx. 10 ° 0, wherein a hydrogen-rich gas is separated from a liquid product with a high oot number, commonly referred to as a reformate. Preferably, at least a portion of the hydrogen-rich gas is passed through an adsorption zone containing an adsorbent which is selective to water. The resulting virtually anhydrous hydrogen stream is then recycled back to the reforming zone by a suitable compressor. The liquid phase from the separation zone is generally treated in a fractionation system to adjust its butane concentration and thus regulate the volatility of the resulting reformate.

The conditions used in the numerous other hydrocarbon conversions which fall within the scope of the present invention are those usually used for the particular reaction or combination of reactions to be performed. Eg. conditions for isomerization of alkyl aromatic hydrocarbons include a temperature of about 0 ° 0 to approx. 538 ° C, a pressure of from atmospheric pressure to approx. 102 ato, a molar ratio of hydrogen to hydrocarbon of fra.ca. 0.5: 1 to approx. 20: 1 and a liquid flow rate (VSH) - calculated as the liquid volume of the charge mixture, as per hour comes into contact with the catalyst, divided by the volume of catalyst found in the conversion zone - from approx. 0.5 to 20 volumes / volume / hour. In just the same way, hydrocracking conditions comprise a pressure of from approx. 34 ato to approx. 204 ato, a temperature of approx. 204 ° 0 to approx. 482 ° C, a VSH of approx. 0.1 to approx. 10 rpm / rpm / hour and a hydrogen circulation amount of 178 to 7,1780 Nos. kiloliters of charge.

In reforming the invention, the applied pressure in the range of approx. 3.4 ato to approx. 68 ato, the preferred pressure being from approx. 6.8 ato to approx. 40.8 ato. It is a particular advantage of the reforming process of the invention that it permits stable operation at lower pressures than has been used previously with good results in so-called "continuous" reforming systems, i.e. reform in periods of approx. 5.25 to approx. 70 kiloliter charge or more per kg of catalyst without regeneration. In other words, the catalyst of the invention, when coupled with a practically anhydrous reforming environment, allows the operation of a continuous reforming system to be carried out at a lower pressure, i.e. 6.8-23 »8 ato, with approximately the same or longer catalyst life before regeneration than has previously been realized with conventional higher pressure catalysts, i.e. 27.2-40.8 ato. On the other hand, the stability feature of the present invention enables reforming to be carried out at pressures of 27.2-40.8 ato to achieve substantially increased catalyst life before regeneration.

Similarly, the temperature required for optimal reforming is generally lower than that required for similar reforming using a known high quality catalyst. The substantial and desirable properties of the present invention are a consequence of the improved selectivity of the present catalyst for the octane number enhancing reactions which are preferably induced by a typical reforming. As a result, the present invention requires for optimum reforming a temperature of between approx. 427 ° 0 and approx. 593 ° C, preferably between about 482 ° 0 and approx. 566 ° 0th The initial choice of temperature within this wide range is made primarily as a function of the desired octane number in the reformate product, taking into account the characteristics of the charge mix and catalyst. Then, during operation, the temperature is slowly increased to compensate for the inevitable deactivation that occurs to provide a constant octane number product. It is an advantage of the present invention that the rate at which the temperature is to be increased to maintain a constant octane product is substantially lower for the present catalyst than for a high quality reforming catalyst prepared in exactly the same manner. as the catalyst of the invention, except that the rhenium component is omitted. Moreover, when using the catalyst of the invention, the loss of all 05 + yield for a given temperature increase is substantially lower than that of a known high quality reforming catalyst.

According to the reforming process in question, sufficient hydrogen is supplied to provide from ca. 2.0 to approx.

20 moles of hydrogen per moles of hydrocarbon entering the reforming zone, with excellent results being obtained from approx. 7 to approx. 10 moles of hydrogen are added per day. moles of hydrocarbon. Similarly, the VSH used in reforming is selected in the range from approx. 0.1 to approx. 10.0 volume / volume / hour, with a value of between approx. 1.0 and approx. 5.0 volume / volume / hour is preferred. In fact, it is a further advantage of the present invention that, for the same severity level, it allows the operation to be carried out at higher YSH than can normally be achieved by a stable, continuous reforming process with a known high quality reforming catalyst. This unexpected property of the catalyst of the invention is believed to be due to its unusual reaction to temperature variations. When using conventional reforming catalysts at a specified severity level, it is usually necessary to operate at low temperature and low YSH because the reaction of the catalyst to higher temperature is a greatly increased hydrocracking with accompanying decrease in C5 + yield. However, the catalyst of the invention does not react to higher temperatures in the expected manner, as the amount of hydrocracking experienced at the same temperature is substantially lower compared to that experienced with conventional reforming catalysts. Accordingly, the catalyst of the present invention permits a given level of severity to be achieved by operation at higher temperatures and higher YSH than has previously been possible by a continuous reforming process. This latter advantage is of immense economic importance as it permits a continuous reforming process to be run at the same yield level with a catalyst stock smaller than that previously required with conventional reforming catalysts and without exceeding the catalyst lifetime before regeneration.

The following examples are included for further illustration of the preparation of the composite catalyst of the invention and its use in the conversion of hydrocarbons.

16 141606

Example 1

This example illustrates the advantages associated with the preferred dry prune reduction step used in preparing the catalyst of the invention, the results obtained with dry reduction and with wet reduction being contrasted. This latter situation, as will be well known to those skilled in the art, is typical of the situation encountered when a hydrocarbon conversion catalyst is commercially launched without any attempt to regulate the amount of water in the conversion plant.

An alumina support material comprising 1.6 mm spheres is prepared by forming an aluminum hydroxyl chloride, etc., by dissolving aluminum hail in hydrochloric acid, adding hexamethylenetetramine to the sun, gelatinizing the resulting solution by dropping it into an oil bath to form particles of an alumina hydrogel, aging and washing the resulting particles, and finally drying and calcining the aged and washed particles to form gamma alumina particles containing ca.

0.3% by weight of bound chloride. Further details of this method can be found in U.S. Patent No. 2,620,314.

The resulting gamma alumina particles are then contacted with an impregnation solution containing chloroplast. Tinic acid, hydrogen chloride and perrhenic acid in quantities giving a finished composite material containing 0.60% by weight platinum, 0.2% by weight rhenium and 0.85% by weight bound chloride, all calculated as elemental. Next, the impregnated balls are dried at a temperature of 149 ° C for approx. 1 hour and alicinated in an air atmosphere at a temperature of approx. 524 ° 0 for approx. 1 hour.

The resulting impregnated particles are then divided into two groups, A and B. Next, the group is subjected. A a wet reduction pretreatment by contacting it with a hydrogen stream containing approx. 500 ppm H 2 O by volume at a temperature of approx. 549 ° C, a pressure slightly above atmospheric pressure and a hydrogen flow rate through the catalyst particles, giving a gas flow rate (GSH) of approx. 720 volume / volume / hour. This contact is continued for approx. 1 hour. A sample of this catalyst, when subjected to X-ray analysis, appears to contain metallic crystallites with an average size of 200 Å. The resulting catalyst is referred to as Catalyst A.

17 141606

Next, the Group B particles are reduced by a practically anhydrous hydrogen stream (i.e. containing less than 1 ppm H 2 O by volume) under conditions identical to those listed above. The resulting catalyst is referred to as Catalyst B. X-ray analysis of a sample of this catalyst shows that it contains metallic crystallites of an average size of less than ca. 50 1.

Thereafter, catalysts A and B are each subjected to a high-severity assessment sample designed to determine their relative activity, selectivity and stability to the conversion of hydrocarbons. This test consists of a charge mixture with a boiling range of approx. 93 ° C to 204 ° C and a low octane count of approx. 50 El clear (ASIM test method no. D908-65) in the presence of hydrogen is contacted with the catalyst in a laboratory scale reforming plant, which includes a reactor containing the catalyst, a hydrogen separation zone, a debut analyzer column and suitable heating, condensation and pumping means, etc.

In the plant, a hydrogen recycle stream and the charge mixture are mixed and the mixture is heated to the desired conversion temperature. The resulting mixture is then passed down through a reactor containing the catalyst as a fixed mass. A discharge stream is then withdrawn from the bottom of the reactor, cooled to approx. 13 ° C and conducted to the separation zone, in which a hydrogen-rich, gaseous phase is separated from a liquid phase. Part. of the gaseous phase is continuously recycled to maintain the desired molar ratio of hydrogen to hydrocarbon and the excess is removed in accordance with the pressure of the plant and recovered as excess separator gas. The liquid phase withdrawn from the separation zone is directed to the debutizer column, in which light products are removed via the top, and a

Cc + current is recovered as a base product. The conditions used in both experiments are an inlet temperature of the reactor of 510 0, a discharge pressure of the reactor of 6.8 ato, a YSH of 1.5 vol / vol / hr and a molar ratio of hydrogen to hydrocarbon. at the 10: 1 reactor access. After a 4 hour line-out period, the results shown in Table I are obtained by a 20 hour experiment.

18 141606

hole) or I

Results of Reform Comparison Trials

Catalyst A B

0 c tantalum of product, P-l clear 90.3 101.4

Aromatic compounds, volume of feed mixture 42.0 60.0 0 +, space feed 70.2 76.1

Hydrogen, m 2 / hr of feed mix 231 267

From these data, the beneficial effects of the dry reduction appear as a remarkable improvement in activity of catalyst B as measured by the octane number of the product and by a significant improvement in selectivity as measured by the C₂ + yield and hydrogen production. Similarly, the relative production of the aromatics by the catalysts shows greater dehydration slope for catalyst B.

Example 2

Better examples show the results of a series of high-severity evaluation experiments conducted with the catalyst of the invention and with a catalyst prepared in exactly the same way, except that rhenium was not included in the latter catalyst. These experiments have been conceived to expose the catalyst to conditions that would accelerate any instability differences they might have.

A number of catalysts are prepared in the manner described in Example 1. However, the concentration of the various components of the impregnation solution is varied to adjust the concentration of the metallic components of the finished catalysts to the values given in Table II. All the catalysts were subjected to the dry piss reduction step described in Example 1.

label II

Catalyst composition - weight - $

Catalyst Pt Re Cl C 0.75 0.85 B 0.75 · 0.1 0.84 E 0.75 0.2 0.83 S 0.55 0.2 0.81 19 141606

Catalyst C is representative of known high-quality and dual-function catalysts and is included here for comparison purposes. The other catalysts represent catalysts of the invention.

These catalysts are individually subjected to a heavy Kuwait naphtha reforming experiment with the characteristics shown in Table III.

fable III

Analysis of Heavy Kuwaitnaphtha Density (15.6 ° C / 15.6 ° C) 0.7375

Initial boiling point, ° 0 84 10 # boiling point, ° C 96 50 # boiling point, ° C 124 90 # boiling point, ° 0 161

Final boiling point, ° C 182

Sulfur, ppm by weight 0.5

Nitrogen, ppm by weight 0.1

Aromatic Compounds, Spacecraft- # 8

Paraffins, space.- # 71

Naphthenes, space.- # 21

Water, ppm 5.9

Octantal, F-l Clear 40.0

All of these experiments are carried out in a reforming system which, in both flow scheme and structure, is practically identical to that described in Example 1, with the exception, however, that a high surface area sodium adsorbent is used on the hydrogen recycle line to remove virtually all water. from there. Thus, all these tests are carried out with an equivalent water content of approx. 5.9 ppm HgO at the approach to the reform zone, which content is based on the naphtha charged thereto.

In addition, all tests are carried out at a pressure of 6.8 ato using hydrogen at an amount of 10 moles per liter. moles of hydrocarbon in the naphtha feed mixture and at a VSH of 1.5 volume / volume / hour.

In accordance with standard practices for continuous reforming systems, B selects an intended octane number of 100 P-l clear, and the conversion temperature in the reforming zone is continuously adjusted for all attempts to obtain this octane number.

Each trial consisted of a period for establishing smooth operation followed by six 24-hour trial periods. The results of the experiments are listed in Table IV.

20 141606 + ΙΑ Ο

VS

ft (D I _ _

A · O -si- H O LA O

in-ii'M · ** · »·» · * · * O> 3 E U3 ΙΑ IA f Ifi AAP c— t-— t— C "- t-— t— cd ft p 02 ft— 'r * 3

H

cd "v A and cd ft

go .go t- CM VO OS H fA

QJO ft CM CM CM LA LA

Eh I LA LA LA LA LA LA LA

& D +

ft. LA

02 O

Sh O VS &

Oh. Φ Φ I ^ _

02 JJ OD O LA N O! A

p A ft a, a * a> a »a * a, φ Ο> = E IA LD VO VO ^ - AD ί3 t— - t— t" - t— t— t— -Η ΐί Ό f) HW ft '-' • H t> 3 A H.

cd cd · »-P A - 02 Cd ft„

i4 SO 4 CO Ol LO OV

02 C & 3 Η H CM CM CM CM

ft eh la la la lA la LA

φ u Φ? H +

02 LA

Η Oh

φ o ^ O ft CD I _ cd -P · H OV CM Ο H 0 \ · ** »»>> * * ft O hS VOLA ^ -ff-ft · ^ cd a A p C— C— -b— t - t— t—

Cd ft P

p m ft ^ Φ 5¾ «Ρ rH.

cd cd · »

A A

H cd ft d M EO LA A N O CVl

m (DO r-L H CM CM ΙΑ IA

<D EH LA LA LA LA LA LA LA

Pi! +

> LA

Η Oh

I-I

<D Ο Φ 1 _ „A A · LA LA LA O VO 00 (d p A ft av a> av ai av ai

Eh O i?) E VO lA Ht A CM P

A A p t— t— C—— C— t—

cd ft u

02 ft w> 3 r-! cd ·> A · cd ft

ώ SO t— t- H LA t- H

(DO H CVI A A A Ht

Eh LA LA LA LA LA LA LA

O ft O · H Sh fid rl (Μ ΙΛ 4 invo Φ ft 21 141606

As explained above, the temperature required to obtain the intended octane at constant conditions for the same charge mixture is a good measure of the catalyst's real activity. In accordance with this distinction, it can be seen that catalysts D, E and F are all more active throughout the experiment than catalyst C. For example. catalyst E is 3 * 0 ° C more active at the start of the experiment, 9.0 ° C more active at the end of the 2nd period, 9.0 ° C more active at the end of the 3 · period, 11.0 ° C more active at the end the end of the 4th period, 11.0 ° C more active at the end of the 5 · period and 12.0 ° C more active at the end of the 6th period.

Similarly, the C + + yield in volume at the same octane number is a prime indicator of catalyst selectivity for reforming reactions. Here, the catalysts D, E and P, the catalysts of the invention, show substantially better average yield over the total test period. Eg. Catalyst E shows an average CL + yield of approx. 76.0% by volume for the entire recovery period, in contrast to the average yield of catalyst C, the control catalyst, of approx. 74.0 by volume.

As mentioned above, the stability of a reforming catalyst used to obtain a product with a constant octane reflects in the rate of change of temperature and the C unit of time. Table V shows these values for catalysts C, D, E and F as well as the amount of carbon in weight found on the catalysts after the experiments.

Table V - Average stability data

Catalyst AT, ° C / kg / kg K AC, - +, vol. - # / kl / kg Weight # carbon C 163.6 -12.9 4.90 D 147.7 - 6.3 6.50 E + 4.1, 2 + 2.9 6.53 P +44.5 - 8.6 4.95 x kl / kg = kiloliters of naphtha charged per kilogram of catalyst

It will be appreciated that the magnitudes of these figures are not representative of the figures that would be obtained at the lower level of stringency which is commercial practice, rather reflecting the strict conditions used in the present experiment. From Table V, it can be seen that the catalysts of the invention are all substantially more stable than the control, both in temperature and in C + + yield. In fact, catalyst E was found to have a positive slope for the C 2+ yield over the relatively short experimental period. From this data, the superior stability of the catalysts in question is immediately evident.

The data given for the amount of carbon by weight of the catalyst shows that the catalysts of the invention do not appear to act to suppress the coke formation on the catalyst and it appears that the essential feature is rather that their performance is far less sensitive to the presence of coke on the catalyst than is the case for conventional reforming catalysts.

Example 5

This example shows the adverse effects of the presence of water during a reforming with the catalyst of the invention.

The catalysts used in all experiments are identical to the catalyst E. used in Example 2

The tests are all conducted in a plant having identical flow chart and using the same conditions used in Example 2, including the use of high surface area sodium for drying the recycle hydrogen. Accordingly, the charge mixture is the only source of water in the system.

To the Kuwait naphtha described in Example 2, tertiary butyl alcohol is added to provide the amounts of water shown for each test in Table VI.

Each trial consisted of a "line-out" period followed by a 24 hour trial period. The results of the experiments are listed in Table VI.

Table VI - Results of water studies

Pre-Dpm. H20 Temperatures search in charge (weight) for the desired octane number, PC C4 +, space- ^ 15 514 75.8 2 25 502 74.1 5 50 519 75.0 4 100 525 68.0 5 150 552 65, 2 6 500 541 51.2 '23 141606

From this table it can be seen that the C + + yield at water volumes above 50 ppm. goes down sharply and the temperature needed to achieve an octane of 100 F-l Clear rises fairly rapidly. Apparently, the hydrocracking function of the catalysts herein is highly sensitive to the presence of water, and at a water content above ca. 50 ppm. (equivalent water) in the feed mixture, the hydrocracking activity of the catalyst begins to dominate and causes a sharp deterioration in the overall performance of the catalyst for reforming. However, this effect of water may be of the utmost importance when the catalyst of the present invention is used in a hydro cracking.

Example 4

A composite catalyst is prepared in accordance with the general method of Example 1. The resulting composite catalyst is subjected to the dry prairie reduction step described in Example 1. The resulting reduced composite material is then presulfated by contacting it with a gaseous mixture containing a molar ratio of Hg to HgS of approx. 10: 1 at a temperature of approx. 550 ° C, a pressure slightly above atmospheric pressure and a gas flow rate (GSH) of approx. 700 volumes / room-catch / hour. Contact will continue for approx. 1 hour. Analysis of the resulting pre-reduced and presulfated catalyst shows that it contains 0.75 wt% platinum, 0.2 wt% rhenium, 0.85 wt% chloride and 0.1 wt% sulfur, all calculated as elemental.

The resulting catalyst is used in a test plant size reforming plant to reform a light Kuwait Charge mixture with the properties shown in Table VII.

Table VII - Lightweight Kuwaiti Charge Blend Properties

Distillation ASTM Test Method No. D-86

Initial boiling point 82-8j5 ° C

10 $ distilled 92-95 ° C

50 $ distilled 97-98 ° C

50 $ distilled 101-102 ° C

70 $ distilled 107-108 ° C

90 $ distilled 117-118 ° C

Final Boiling Point 151-153¾ 24 1A1606 Table YIX (continued) Density, (15.6 ° C / 155.6 ° C) o, 7200-0, T18l

Paraffins, Spacecraft- $ 76

Naphthens, spacecraft .- $ 18

Aromatic compounds, _. spacious- $ 6

Water, ppm (weight) <1

Sulfur, ppm (weight) <1

The flow chart used in this plant is essentially the same as that described in Example 1, except that high surface area drying agents are used to dry both the charge mixture and the hydrogen stream before being charged to the plant.

The conditions used for this experiment include an intended octane number of 96.0 Fl Clear, a VSH of 1.0 volume / volume / hour until a catalyst lifetime of 1.9 kI / kg, and a VSH of 2.0 volume / volume. catch / hour thereafter, a pressure of 13.6 ato and a molar ratio of hydrogen to hydrocarbon of 7.0.

The results of this experiment are shown in Table VIII in the form of C₂ + yield in volume percentage, H₂ yield and conversion temperature necessary to obtain the desired octane as a function of catalyst lifetime measured in kiloliters of charge per kilogram. kilogram of catalyst (kl / kg).

Table VIII - Results of experimental plant studies 3

Catalyst - C (- + - yield, mmf.-fo H2 yield, no.

lifetime, kl / kg Temp, ° C of charge_cl charge_ 0.07 482 74.0 '188 0.35 486 73.0 184 0. 7 490 73.9 180 1, -05 493 73.5 179 1, 4 496 73.0 178 1.75 497 72.8 177 VSH increased to 2.0 2.1 517 73.8 178 2.45 518 73.7 178 2.8 520 73.3 178 3.15 521 73.0 178 25 141606

The results of this experiment show the remarkable stability of the catalyst of the invention. Particularly significant is the observed average C, + decrease of approx. 0.71 volume percent / kg / kg and a temperature increase of approx. 8.9 ° C / kg / kg for the catalyst life up to 1.9 kl / kg, which contrasts with the expected decline of approx. -5.5 ^ by volume / kg / kg and increase of approx. 9.5 ° C / kg / kg for a catalyst prepared in exactly the same manner as used herein except that the rhenium component was not included.

Even more surprising are the results that emerge when VSH doubles at a catalyst lifetime of 1.9 kl / kg. The catalyst of the invention exhibited improved yield and temperature stability under these conditions, which is in sharp contrast to the sharp decline in C, + yield with accompanying accelerated catalyst instability previously encountered with a conventional platinum-containing reforming catalyst.

Claims (5)

26 141606 P a t e n t k r a v. A process for reforming a hydrocarbon in which the hydrocarbon is contacted at elevated temperature and pressure and in the presence of hydrogen by a composite catalyst, characterized in that a catalyst comprising alumina, a metallic component of the plate group, is used. a halogen component and a rhenium component, said components being present in amounts which in the composite catalyst on the elemental basis provide from ca. 0.1 to approx. 1.5% by weight of halogen, from approx. 0.05 to approx. 1.0% by weight plate group metal and from approx. 0.05 to approx. 1.0% by weight of rhenium. Process according to claim 1, characterized in that the composite catalyst also contains a sulfur component in an amount of between approx. 0.05 and 0.5% by weight of the composite catalyst, calculated as elemental. Composite catalyst comprising alumina and intended for carrying out the process according to claim 1 or 2, characterized in that the alumina is combined with a metallic component of the plate group, a halogen component and a rhenium component, said components being present in amounts as in the composite catalyst, on an elemental basis, provides from ca. 0.1 to approx. 1.5% by weight of halogen, from approx. 0.05 to approx. 1.0% by weight plate group metal and from approx. 0.05 to approx. 1.0% by weight of rhenium. Composite catalyst according to claim 3, characterized in that it also contains a sulfur component in an amount of from approx. 0.05 to approx. 0.5% by weight of the catalyst weight. Composite catalyst according to claim 3 or 4, characterized in that the combined weight of the rhenium component and the metallic component of the plate group is from approx. 0.2 to approx. 1.5% by weight of the catalyst weight, calculated on an elemental basis.